a cool guy

“Describe how to determine the height of a skyscraper with a barometer.” To this question, set on a physics paper, one student replied:

“Tie a long string to the barometer, then lower it to the ground. The height of the building is the length of the string plus the length of the barometer.
The student failed, but appealed on the grounds that the answer was scientifically correct. So the University appointed an arbiter. Since the answer given was felt to show no particular grasp of physics, the student was asked to come in and show, in six minutes, that he really did understand the basics of the physics behind the question.

For five minutes the student sat in silence, then answered, “OK, drop it from the roof and measure the time it takes to hit the ground. The height of the building can then be worked out from the formula H = 0.5g x t squared.

Or, if the sun is out, measure the height of the barometer and the length of its shadow, then work out the height of the building from the length of the skyscraper’s shadow.

You could also tie a string to the barometer and swing it like a pendulum, first at ground level and then on the roof. The height is worked out by the difference in the gravitational restoring force T =2 pi sqr root (l /g).

However, if you lacked imagination, you could, of course, use the barometer to measure the air pressure on the roof and on the ground, and convert the difference in millibars into feet to give the height of the building.”

The student was Niels Bohr, now known as the father of the quantum model of the atom, and a winner of the Nobel Prize for physics!